QCD Studies and alpha_s Measurements at LEP

TL;DR

This paper reports on measurements of the strong coupling constant alpha_s using event shape data from LEP across various energies, including photon radiation events and four-jet rates, to study the running of alpha_s.

Contribution

It provides a combined alpha_s(M_Z) value from LEP data and explores its energy dependence through novel methods like photon radiation and four-jet rates.

Findings

Determined alpha_s(M_Z) with high precision.

Confirmed the running of alpha_s across energies.

Compared different measurement techniques for consistency.

Abstract

The LEP experiments have measured event shapes using data taken at e+e- center-of-mass energies ranging from 91 GeV to 209 GeV. Using the final LEP event shape measurements, a combined value of the strong coupling constant alpha_s(M_Z) has been extracted. Events with photon radiation have been used to extend the measurements to lower center-of-mass energies sqrt(s') to study the running of alpha_s. Alternative alpha_s measurements using four-jet rates have also been performed.